Toddlers just learning to speak associate words with shape, not size or texture. Anything shaped like a telephone, for instance, might be called “phone.”

"Dali, my 12 years old golden retriever"

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But a new study suggests that dogs tend to associate words with size rather than shape.

This difference makes it “very doubtful that there is a single mammalian feature in word learning,” said Emile van der Zee, a psychologist at the University of Lincoln in England and the first author of the study, which appears in the journal PLoS One. “This study may help us understand why humans are more special when it comes to learning language.”

The researchers worked with Gable, a 5-year-old Border collie with an understanding of more than 40 words. The dog was shown a horseshoe-shaped object that the scientists called a “dax.”

After some training, the dog began to identify other objects of similar size with the same name. After taking the object home for about a month, Gable also began to associate the word with other objects of similar texture, but never objects that were simply of similar shape.

The smells of the objects were kept neutral, but the results may differ if scent is incorporated, Dr. van der Zee said.

“That would be something that we would like to do in our future research,” he said, adding that he would like to repeat the study with other mammals, including pigs and primates.